A structure such as a bumper beam, a side sill, or a B pillar is provided on front, rear, left, and right sides of a vehicle body. In the related art, in general, such a structure is formed of a metal material. However, recently, a reduction in the weight of a vehicle body has been desired, for example, in order to improve the fuel efficiency. Therefore, a research on replacement of the metal material with a resin material has been actively carried out.
In order not only to reduce the weight but also to protect passengers during collision, it is required that the structure has an excellent impact absorbing property. In addition, during collision, it is required that fracturing does not occur at a position other than a fracture origin where fracturing is estimated to occur during the design phase. In order to satisfy the requirements, for example, a method of disposing ribs on the entire front surface of a structure is studied in Patent Document 1.
On the other hand, a configuration of providing a fragile portion at a load input position in order to control the fracture origin during collision is studied in Patent Document 2